/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young (eay@cryptsoft.com).
 * The implementation was written so as to conform with Netscapes SSL.
 *
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
 *
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young (eay@cryptsoft.com)"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
 *
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * The licence and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution licence
 * [including the GNU Public Licence.] */

#ifndef OPENSSL_HEADER_STACK_H
#define OPENSSL_HEADER_STACK_H

#include <openssl/base.h>

#include <openssl/type_check.h>

#if defined(__cplusplus)
extern "C" {
#endif

// A stack, in OpenSSL, is an array of pointers. They are the most commonly
// used collection object.
//
// This file defines macros for type safe use of the stack functions. A stack
// of a specific type of object has type |STACK_OF(type)|. This can be defined
// (once) with |DEFINE_STACK_OF(type)| and declared where needed with
// |DECLARE_STACK_OF(type)|. For example:
//
//   typedef struct foo_st {
//     int bar;
//   } FOO;
//
//   DEFINE_STACK_OF(FOO)
//
// Although note that the stack will contain /pointers/ to |FOO|.
//
// A macro will be defined for each of the sk_* functions below. For
// STACK_OF(FOO), the macros would be sk_FOO_new, sk_FOO_pop etc.

// stack_free_func is a function that frees an element in a stack. Note its
// actual type is void (*)(T *) for some T. Low-level |sk_*| functions will be
// passed a type-specific wrapper to call it correctly.
typedef void (*stack_free_func)(void* ptr);

// stack_copy_func is a function that copies an element in a stack. Note its
// actual type is T *(*)(T *) for some T. Low-level |sk_*| functions will be
// passed a type-specific wrapper to call it correctly.
typedef void* (*stack_copy_func)(void* ptr);

// stack_cmp_func is a comparison function that returns a value < 0, 0 or > 0
// if |*a| is less than, equal to or greater than |*b|, respectively.  Note the
// extra indirection - the function is given a pointer to a pointer to the
// element. This differs from the usual qsort/bsearch comparison function.
//
// Note its actual type is int (*)(const T **, const T **). Low-level |sk_*|
// functions will be passed a type-specific wrapper to call it correctly.
typedef int (*stack_cmp_func)(const void** a, const void** b);

// stack_st contains an array of pointers. It is not designed to be used
// directly, rather the wrapper macros should be used.
typedef struct stack_st {
    // num contains the number of valid pointers in |data|.
    size_t num;
    void** data;
    // sorted is non-zero if the values pointed to by |data| are in ascending
    // order, based on |comp|.
    int sorted;
    // num_alloc contains the number of pointers allocated in the buffer pointed
    // to by |data|, which may be larger than |num|.
    size_t num_alloc;
    // comp is an optional comparison function.
    stack_cmp_func comp;
} _STACK;

#define STACK_OF(type) struct stack_st_##type

#define DECLARE_STACK_OF(type) STACK_OF(type);

// These are the raw stack functions, you shouldn't be using them. Rather you
// should be using the type stack macros implemented above.

// sk_new creates a new, empty stack with the given comparison function, which
// may be zero. It returns the new stack or NULL on allocation failure.
OPENSSL_EXPORT _STACK* sk_new(stack_cmp_func comp);

// sk_new_null creates a new, empty stack. It returns the new stack or NULL on
// allocation failure.
OPENSSL_EXPORT _STACK* sk_new_null(void);

// sk_num returns the number of elements in |s|.
OPENSSL_EXPORT size_t sk_num(const _STACK* sk);

// sk_zero resets |sk| to the empty state but does nothing to free the
// individual elements themselves.
OPENSSL_EXPORT void sk_zero(_STACK* sk);

// sk_value returns the |i|th pointer in |sk|, or NULL if |i| is out of
// range.
OPENSSL_EXPORT void* sk_value(const _STACK* sk, size_t i);

// sk_set sets the |i|th pointer in |sk| to |p| and returns |p|. If |i| is out
// of range, it returns NULL.
OPENSSL_EXPORT void* sk_set(_STACK* sk, size_t i, void* p);

// sk_free frees the given stack and array of pointers, but does nothing to
// free the individual elements. Also see |sk_pop_free_ex|.
OPENSSL_EXPORT void sk_free(_STACK* sk);

// sk_pop_free_ex calls |free_func| on each element in the stack and then frees
// the stack itself. Note this corresponds to |sk_FOO_pop_free|. It is named
// |sk_pop_free_ex| as a workaround for existing code calling an older version
// of |sk_pop_free|.
OPENSSL_EXPORT void sk_pop_free_ex(_STACK* sk, void (*call_free_func)(stack_free_func, void*),
                                   stack_free_func free_func);

// sk_insert inserts |p| into the stack at index |where|, moving existing
// elements if needed. It returns the length of the new stack, or zero on
// error.
OPENSSL_EXPORT size_t sk_insert(_STACK* sk, void* p, size_t where);

// sk_delete removes the pointer at index |where|, moving other elements down
// if needed. It returns the removed pointer, or NULL if |where| is out of
// range.
OPENSSL_EXPORT void* sk_delete(_STACK* sk, size_t where);

// sk_delete_ptr removes, at most, one instance of |p| from the stack based on
// pointer equality. If an instance of |p| is found then |p| is returned,
// otherwise it returns NULL.
OPENSSL_EXPORT void* sk_delete_ptr(_STACK* sk, const void* p);

// sk_find returns the first value in the stack equal to |p|. If a comparison
// function has been set on the stack, equality is defined by it, otherwise
// pointer equality is used. If the stack is sorted, then a binary search is
// used, otherwise a linear search is performed. If a matching element is found,
// its index is written to
// |*out_index| (if |out_index| is not NULL) and one is returned. Otherwise zero
// is returned.
//
// Note this differs from OpenSSL. The type signature is slightly different, and
// OpenSSL's sk_find will implicitly sort |sk| if it has a comparison function
// defined.
OPENSSL_EXPORT int sk_find(const _STACK* sk, size_t* out_index, const void* p,
                           int (*call_cmp_func)(stack_cmp_func, const void**, const void**));

// sk_shift removes and returns the first element in the stack, or returns NULL
// if the stack is empty.
OPENSSL_EXPORT void* sk_shift(_STACK* sk);

// sk_push appends |p| to the stack and returns the length of the new stack, or
// 0 on allocation failure.
OPENSSL_EXPORT size_t sk_push(_STACK* sk, void* p);

// sk_pop returns and removes the last element on the stack, or NULL if the
// stack is empty.
OPENSSL_EXPORT void* sk_pop(_STACK* sk);

// sk_dup performs a shallow copy of a stack and returns the new stack, or NULL
// on error.
OPENSSL_EXPORT _STACK* sk_dup(const _STACK* sk);

// sk_sort sorts the elements of |sk| into ascending order based on the
// comparison function. The stack maintains a |sorted| flag and sorting an
// already sorted stack is a no-op.
OPENSSL_EXPORT void sk_sort(_STACK* sk);

// sk_is_sorted returns one if |sk| is known to be sorted and zero
// otherwise.
OPENSSL_EXPORT int sk_is_sorted(const _STACK* sk);

// sk_set_cmp_func sets the comparison function to be used by |sk| and returns
// the previous one.
OPENSSL_EXPORT stack_cmp_func sk_set_cmp_func(_STACK* sk, stack_cmp_func comp);

// sk_deep_copy performs a copy of |sk| and of each of the non-NULL elements in
// |sk| by using |copy_func|. If an error occurs, |free_func| is used to free
// any copies already made and NULL is returned.
OPENSSL_EXPORT _STACK* sk_deep_copy(const _STACK* sk, void* (*call_copy_func)(stack_copy_func, void*),
                                    stack_copy_func copy_func, void (*call_free_func)(stack_free_func, void*),
                                    stack_free_func free_func);

// Deprecated functions.

// sk_pop_free behaves like |sk_pop_free_ex| but performs an invalid function
// pointer cast. It exists because some existing callers called |sk_pop_free|
// directly.
//
// TODO(davidben): Migrate callers to bssl::UniquePtr and remove this.
OPENSSL_EXPORT void sk_pop_free(_STACK* sk, stack_free_func free_func);

// Defining stack types.
//
// This set of macros is used to emit the typed functions that act on a
// |STACK_OF(T)|.

#if !defined(BORINGSSL_NO_CXX)
extern "C++" {
BSSL_NAMESPACE_BEGIN
namespace internal
{
    template <typename T> struct StackTraits {
    };
} // namespace internal
BSSL_NAMESPACE_END
}

    #define BORINGSSL_DEFINE_STACK_TRAITS(name, type, is_const)                                                        \
        extern "C++" {                                                                                                 \
        BSSL_NAMESPACE_BEGIN                                                                                           \
        namespace internal                                                                                             \
        {                                                                                                              \
            template <> struct StackTraits<STACK_OF(name)> {                                                           \
                static constexpr bool kIsStack = true;                                                                 \
                using Type = type;                                                                                     \
                static constexpr bool kIsConst = is_const;                                                             \
            };                                                                                                         \
        }                                                                                                              \
        BSSL_NAMESPACE_END                                                                                             \
        }

#else
    #define BORINGSSL_DEFINE_STACK_TRAITS(name, type, is_const)
#endif

#define BORINGSSL_DEFINE_STACK_OF_IMPL(name, ptrtype, constptrtype)                                                    \
    DECLARE_STACK_OF(name)                                                                                             \
                                                                                                                       \
    typedef void (*stack_##name##_free_func)(ptrtype);                                                                 \
    typedef ptrtype (*stack_##name##_copy_func)(ptrtype);                                                              \
    typedef int (*stack_##name##_cmp_func)(constptrtype * a, constptrtype * b);                                        \
                                                                                                                       \
    OPENSSL_INLINE void sk_##name##_call_free_func(stack_free_func free_func, void* ptr)                               \
    {                                                                                                                  \
        ((stack_##name##_free_func)free_func)((ptrtype)ptr);                                                           \
    }                                                                                                                  \
                                                                                                                       \
    OPENSSL_INLINE void* sk_##name##_call_copy_func(stack_copy_func copy_func, void* ptr)                              \
    {                                                                                                                  \
        return (void*)((stack_##name##_copy_func)copy_func)((ptrtype)ptr);                                             \
    }                                                                                                                  \
                                                                                                                       \
    OPENSSL_INLINE int sk_##name##_call_cmp_func(stack_cmp_func cmp_func, const void** a, const void** b)              \
    {                                                                                                                  \
        constptrtype a_ptr = (constptrtype)*a;                                                                         \
        constptrtype b_ptr = (constptrtype)*b;                                                                         \
        return ((stack_##name##_cmp_func)cmp_func)(&a_ptr, &b_ptr);                                                    \
    }                                                                                                                  \
                                                                                                                       \
    OPENSSL_INLINE STACK_OF(name) * sk_##name##_new(stack_##name##_cmp_func comp)                                      \
    {                                                                                                                  \
        return (STACK_OF(name)*)sk_new((stack_cmp_func)comp);                                                          \
    }                                                                                                                  \
                                                                                                                       \
    OPENSSL_INLINE STACK_OF(name) * sk_##name##_new_null(void)                                                         \
    {                                                                                                                  \
        return (STACK_OF(name)*)sk_new_null();                                                                         \
    }                                                                                                                  \
                                                                                                                       \
    OPENSSL_INLINE size_t sk_##name##_num(const STACK_OF(name) * sk)                                                   \
    {                                                                                                                  \
        return sk_num((const _STACK*)sk);                                                                              \
    }                                                                                                                  \
                                                                                                                       \
    OPENSSL_INLINE void sk_##name##_zero(STACK_OF(name) * sk)                                                          \
    {                                                                                                                  \
        sk_zero((_STACK*)sk);                                                                                          \
    }                                                                                                                  \
                                                                                                                       \
    OPENSSL_INLINE ptrtype sk_##name##_value(const STACK_OF(name) * sk, size_t i)                                      \
    {                                                                                                                  \
        return (ptrtype)sk_value((const _STACK*)sk, i);                                                                \
    }                                                                                                                  \
                                                                                                                       \
    OPENSSL_INLINE ptrtype sk_##name##_set(STACK_OF(name) * sk, size_t i, ptrtype p)                                   \
    {                                                                                                                  \
        return (ptrtype)sk_set((_STACK*)sk, i, (void*)p);                                                              \
    }                                                                                                                  \
                                                                                                                       \
    OPENSSL_INLINE void sk_##name##_free(STACK_OF(name) * sk)                                                          \
    {                                                                                                                  \
        sk_free((_STACK*)sk);                                                                                          \
    }                                                                                                                  \
                                                                                                                       \
    OPENSSL_INLINE void sk_##name##_pop_free(STACK_OF(name) * sk, stack_##name##_free_func free_func)                  \
    {                                                                                                                  \
        sk_pop_free_ex((_STACK*)sk, sk_##name##_call_free_func, (stack_free_func)free_func);                           \
    }                                                                                                                  \
                                                                                                                       \
    OPENSSL_INLINE size_t sk_##name##_insert(STACK_OF(name) * sk, ptrtype p, size_t where)                             \
    {                                                                                                                  \
        return sk_insert((_STACK*)sk, (void*)p, where);                                                                \
    }                                                                                                                  \
                                                                                                                       \
    OPENSSL_INLINE ptrtype sk_##name##_delete(STACK_OF(name) * sk, size_t where)                                       \
    {                                                                                                                  \
        return (ptrtype)sk_delete((_STACK*)sk, where);                                                                 \
    }                                                                                                                  \
                                                                                                                       \
    OPENSSL_INLINE ptrtype sk_##name##_delete_ptr(STACK_OF(name) * sk, constptrtype p)                                 \
    {                                                                                                                  \
        return (ptrtype)sk_delete_ptr((_STACK*)sk, (const void*)p);                                                    \
    }                                                                                                                  \
                                                                                                                       \
    OPENSSL_INLINE int sk_##name##_find(const STACK_OF(name) * sk, size_t * out_index, constptrtype p)                 \
    {                                                                                                                  \
        return sk_find((const _STACK*)sk, out_index, (const void*)p, sk_##name##_call_cmp_func);                       \
    }                                                                                                                  \
                                                                                                                       \
    OPENSSL_INLINE ptrtype sk_##name##_shift(STACK_OF(name) * sk)                                                      \
    {                                                                                                                  \
        return (ptrtype)sk_shift((_STACK*)sk);                                                                         \
    }                                                                                                                  \
                                                                                                                       \
    OPENSSL_INLINE size_t sk_##name##_push(STACK_OF(name) * sk, ptrtype p)                                             \
    {                                                                                                                  \
        return sk_push((_STACK*)sk, (void*)p);                                                                         \
    }                                                                                                                  \
                                                                                                                       \
    OPENSSL_INLINE ptrtype sk_##name##_pop(STACK_OF(name) * sk)                                                        \
    {                                                                                                                  \
        return (ptrtype)sk_pop((_STACK*)sk);                                                                           \
    }                                                                                                                  \
                                                                                                                       \
    OPENSSL_INLINE STACK_OF(name) * sk_##name##_dup(const STACK_OF(name) * sk)                                         \
    {                                                                                                                  \
        return (STACK_OF(name)*)sk_dup((const _STACK*)sk);                                                             \
    }                                                                                                                  \
                                                                                                                       \
    OPENSSL_INLINE void sk_##name##_sort(STACK_OF(name) * sk)                                                          \
    {                                                                                                                  \
        sk_sort((_STACK*)sk);                                                                                          \
    }                                                                                                                  \
                                                                                                                       \
    OPENSSL_INLINE int sk_##name##_is_sorted(const STACK_OF(name) * sk)                                                \
    {                                                                                                                  \
        return sk_is_sorted((const _STACK*)sk);                                                                        \
    }                                                                                                                  \
                                                                                                                       \
    OPENSSL_INLINE stack_##name##_cmp_func sk_##name##_set_cmp_func(STACK_OF(name) * sk, stack_##name##_cmp_func comp) \
    {                                                                                                                  \
        return (stack_##name##_cmp_func)sk_set_cmp_func((_STACK*)sk, (stack_cmp_func)comp);                            \
    }                                                                                                                  \
                                                                                                                       \
    OPENSSL_INLINE STACK_OF(name) *                                                                                    \
        sk_##name##_deep_copy(const STACK_OF(name) * sk, ptrtype(*copy_func)(ptrtype), void (*free_func)(ptrtype))     \
    {                                                                                                                  \
        return (STACK_OF(name)*)sk_deep_copy((const _STACK*)sk, sk_##name##_call_copy_func,                            \
                                             (stack_copy_func)copy_func, sk_##name##_call_free_func,                   \
                                             (stack_free_func)free_func);                                              \
    }

// DEFINE_NAMED_STACK_OF defines |STACK_OF(name)| to be a stack whose elements
// are |type| *.
#define DEFINE_NAMED_STACK_OF(name, type)                                                                              \
    BORINGSSL_DEFINE_STACK_OF_IMPL(name, type*, const type*)                                                           \
    BORINGSSL_DEFINE_STACK_TRAITS(name, type, false)

// DEFINE_STACK_OF defines |STACK_OF(type)| to be a stack whose elements are
// |type| *.
#define DEFINE_STACK_OF(type) DEFINE_NAMED_STACK_OF(type, type)

// DEFINE_CONST_STACK_OF defines |STACK_OF(type)| to be a stack whose elements
// are const |type| *.
#define DEFINE_CONST_STACK_OF(type)                                                                                    \
    BORINGSSL_DEFINE_STACK_OF_IMPL(type, const type*, const type*)                                                     \
    BORINGSSL_DEFINE_STACK_TRAITS(type, const type, true)

// DEFINE_SPECIAL_STACK_OF defines |STACK_OF(type)| to be a stack whose elements
// are |type|, where |type| must be a typedef for a pointer.
#define DEFINE_SPECIAL_STACK_OF(type)                                                                                  \
    OPENSSL_STATIC_ASSERT(sizeof(type) == sizeof(void*), #type " is not a pointer");                                   \
    BORINGSSL_DEFINE_STACK_OF_IMPL(type, type, const type)

typedef char* OPENSSL_STRING;

DEFINE_STACK_OF(void)
DEFINE_SPECIAL_STACK_OF(OPENSSL_STRING)

#if defined(__cplusplus)
} // extern C
#endif

#if !defined(BORINGSSL_NO_CXX)
extern "C++" {

    #include <type_traits>

BSSL_NAMESPACE_BEGIN

namespace internal
{

    // Stacks defined with |DEFINE_CONST_STACK_OF| are freed with |sk_free|.
    template <typename Stack> struct DeleterImpl<Stack, typename std::enable_if<StackTraits<Stack>::kIsConst>::type> {
        static void Free(Stack* sk)
        {
            sk_free(reinterpret_cast<_STACK*>(sk));
        }
    };

    // Stacks defined with |DEFINE_STACK_OF| are freed with |sk_pop_free| and the
    // corresponding type's deleter.
    template <typename Stack> struct DeleterImpl<Stack, typename std::enable_if<!StackTraits<Stack>::kIsConst>::type> {
        static void Free(Stack* sk)
        {
            // sk_FOO_pop_free is defined by macros and bound by name, so we cannot
            // access it from C++ here.
            using Type = typename StackTraits<Stack>::Type;
            sk_pop_free_ex(
                reinterpret_cast<_STACK*>(sk),
                [](stack_free_func /* unused */, void* ptr) {
                    DeleterImpl<Type>::Free(reinterpret_cast<Type*>(ptr));
                },
                nullptr);
        }
    };

    template <typename Stack> class StackIteratorImpl
    {
      public:
        using Type = typename StackTraits<Stack>::Type;
        // Iterators must be default-constructable.
        StackIteratorImpl() : sk_(nullptr), idx_(0)
        {
        }
        StackIteratorImpl(const Stack* sk, size_t idx) : sk_(sk), idx_(idx)
        {
        }

        bool operator==(StackIteratorImpl other) const
        {
            return sk_ == other.sk_ && idx_ == other.idx_;
        }
        bool operator!=(StackIteratorImpl other) const
        {
            return !(*this == other);
        }

        Type* operator*() const
        {
            return reinterpret_cast<Type*>(sk_value(reinterpret_cast<const _STACK*>(sk_), idx_));
        }

        StackIteratorImpl& operator++(/* prefix */)
        {
            idx_++;
            return *this;
        }

        StackIteratorImpl operator++(int /* postfix */)
        {
            StackIteratorImpl copy(*this);
            ++(*this);
            return copy;
        }

      private:
        const Stack* sk_;
        size_t idx_;
    };

    template <typename Stack>
    using StackIterator = typename std::enable_if<StackTraits<Stack>::kIsStack, StackIteratorImpl<Stack>>::type;

} // namespace internal

// PushToStack pushes |elem| to |sk|. It returns true on success and false on
// allocation failure.
template <typename Stack>
inline typename std::enable_if<!internal::StackTraits<Stack>::kIsConst, bool>::type PushToStack(
    Stack* sk, UniquePtr<typename internal::StackTraits<Stack>::Type> elem)
{
    if (!sk_push(reinterpret_cast<_STACK*>(sk), elem.get())) {
        return false;
    }
    // sk_push takes ownership on success.
    elem.release();
    return true;
}

BSSL_NAMESPACE_END

// Define begin() and end() for stack types so C++ range for loops work.
template <typename Stack> inline bssl::internal::StackIterator<Stack> begin(const Stack* sk)
{
    return bssl::internal::StackIterator<Stack>(sk, 0);
}

template <typename Stack> inline bssl::internal::StackIterator<Stack> end(const Stack* sk)
{
    return bssl::internal::StackIterator<Stack>(sk, sk_num(reinterpret_cast<const _STACK*>(sk)));
}

} // extern C++
#endif

#endif // OPENSSL_HEADER_STACK_H
